Modular heat sink and method for fabricating same

ABSTRACT

There is described a method for fabricating a modular heat sink, the method comprising: extruding N individual integral heat sink segments using an extrusion process, each one of the N segments corresponding to 1/N of the modular heat sink, N being an integer greater than one; and assembling the N individual integral heat sink segments together in order to obtain the modular heat sink.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation under 35 USC §120 of International patent application no. PCT/CA2009/000551 filed Apr. 24, 2009 entitled MODULAR HEAT SINK AND METHOD FOR FABRICATING SAME, which claims priority under 35 USC §119(e) of Provisional Patent Application bearing Ser. No. 61/048,400, filed on Apr. 28, 2008, the contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to the field of heat dissipation devices, also known as heat sinks.

BACKGROUND OF THE INVENTION

Devices such as electronic circuits and lighting systems usually emit heat while functioning, and this emitted heat can be harmful to the device. For example, an increased temperature can shorten the lifetime of a lighting system and/or decrease its brightness. As a result, cooling the lighting device is required to ensure a long lifetime and/or a high brightness.

Heat sinks can be used to cool heat generating devices. A heat sink cools the device by absorbing and dissipating generated heat. A heat sink is made of a thermal conductive material and has a specific shape which improves the transfer of heat, whereby the shape is specifically determined by a need for greater surface area. Extrusion techniques are usually used to fabricate heat sinks as it is an efficient and cost-saving fabrication technique in comparison to other fabrication processes such as casting or machining. However, when using this fabrication process, the dimensions of heat sinks are limited because of limitations inherent to the extrusion process. Hence, it is not possible to make heat sinks for large lighting systems when using the extrusion process.

Therefore, there is a need for improvements to the methods for fabricating heat sinks adapted to large heat generating devices.

SUMMARY OF THE INVENTION

According to a broad aspect, there is provided a method for fabricating a modular heat sink, the method comprising: extruding N individual integral heat sink segments using an extrusion process, each one of the N segments corresponding to 1/N of the modular heat sink, N being an integer greater than one; and assembling the N individual integral heat sink segments together in order to obtain the modular heat sink.

According to a second broad aspect, there is provided a modular heat sink comprising a N extruded individual integral heat sink segments connected together to form the modular heat sink, each one of the N segments corresponding to 1/N of the modular heat sink, N being an integer greater than one.

The expression “heat sink segment” is to be understood as any device made in a single piece and having heat sink properties. A heat sink segment forms a heat sink when connected to at least another heat sink segment. The characteristics of each heat sink segment, such as the shape and dimensions for example, are defined so that the heat sink segments form the heat sink when connected together and can be fabricated by any adequate type of extrusion process. The heat sink segments being part of the heat sink can be identical. Alternatively, they can have different shapes and/or dimensions and/or be made of different materials.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

FIG. 1 illustrates a heat sink according to the prior art;

FIG. 2 is a flow chart of a method for fabricating a modular heat sink, in accordance with an embodiment;

FIG. 3 is a top view of a quadrant heat sink segment, in accordance with an embodiment;

FIG. 4 is a top view of a cylindrical heat sink made of four heat sink segments as shown in FIG. 2, in accordance with an embodiment;

FIG. 5 is a perspective view of a cubic heat sink segment having a single aperture, in accordance with an embodiment;

FIG. 6A is a perspective view of a heat sink formed of four cubic heat sink segments as shown in FIG. 4, in accordance with an embodiment;

FIG. 6B is a perspective view of a modular heat sink comprising straps to maintain heat sink segments in position, in accordance with an embodiment;

FIG. 7 is a perspective view of a cubic heat sink segment having five apertures, in accordance with an embodiment;

FIG. 8 is a side view of a heat sink formed of two rectangular heat sink segments to form a heat sink as illustrated in FIG. 6, in accordance with an embodiment;

FIG. 9A is a top view of a cubic modular heat sink comprising four apertures, in accordance with an embodiment; and

FIG. 98 is a top view of a modular heat sink provided with seven apertures, in accordance with an embodiment.

It will be noted that throughout the appended drawings, like features are identified by like reference numerals.

DETAILED DESCRIPTION

FIG. 1 illustrates a heat sink 10 according to the prior art. Heat sink 10 comprises a top and a bottom circular surface and a lateral cylindrical surface. The heat sink 10 has a specific shape in order to increase its total surface area that is in contact with a cooling fluid such as air. The lateral surface of the heat sink 10 is provided with fins 12. A central aperture 14 and lateral apertures 16 extend from the top surface to the bottom surface. The fins 12, the central aperture 14 and the lateral apertures 16 increase the total surface area of heat sink 10 that is in contact with air, which allows the cooling of an electronic device to be in physical contact with the heat sink 10.

According to the prior art, heat sinks are made in a single piece. When heat conductive material such as aluminum or copper is used to fabricate heat sinks by extrusion, the size of the heat sink is limited because of the extrusion process. Extrusion can be any adequate fabrication process which consists in pushing material through a die of a desired profile shape. However, a large heat sink fabricated following this process does not present good mechanical properties such as rigidity. These poor mechanical properties are inherent to the extrusion process.

A heat sink is designed in accordance with the characteristics of the object to be cooled, a target temperature for the object, the characteristics of the environment in which the heat sink will be placed, etc. For example, if the modular heat sink is to be used to cool an LED board comprising a plurality of LEDs, the characteristics of the modular heat sink are chosen in accordance with the dimensions of the LED board, the repartition of the LEDs on the LED board, the heat generated by the LEDs, the temperature of the environment in which the heat sink is to be placed, a target temperature for the LED board, etc. The characteristics of a heat sink comprises, but are not limited to, the shape, the dimensions, the material properties such as rigidity for example, and the like. If the characteristics of the heat sink prevent the heat sink from being fabricated in a single piece by extrusion, then the method illustrated in FIG. 2 can be used to fabricate the heat sink.

FIG. 2 illustrates one embodiment of a method 20 for fabricating a modular heat sink. The first step 22 consists in extruding N individual integral heat sink segments using an extrusion process. N is an integer greater than one so that at least two individual integral heat sink segments are extruded. Each one of the N segments corresponds to 1/N of the modular heat sink to be fabricated. The second step 24 consists in assembling the N individual integral heat sink segments together in order to obtain the modular heat sink. In one embodiment, the assembling can consist in releasably connecting the individual integral heat sink segments together. In an alternate embodiment, the assembling can consist in permanently and fixedly securing the individual integral heat sink segments together.

In one embodiment, a heat sink is to be fabricated while using an extrusion process and the heat sink is broken down into two pieces, i.e. two individual integral heat sink segments, each corresponding to one half of the heat sink. In another embodiment, the heat sink is broken down into three pieces, i.e. three individual integral heat sink segments, each corresponding to one third of the heat sink. The breaking down of the heat sink is performed with the desired number of individual integral heat sink segments that can be fabricated in a single piece while using an extrusion process.

In one embodiment, the heat sink to be fabricated is symmetrical and the N individual integral heat sink segments are substantially identical. In another embodiment, the N individual integral heat sink segments are different while each one of the N individual integral heat sink segments corresponds to 1/N of the heat sink. The nature of the differences between the segments can be material, shape, surface area, volume of material, etc.

It should be understood that any assembling means such as male-female connectors, fasteners, adhesive, welding, etc, can be used for releasably or permanently connecting the heat sink segments together. In one embodiment, the heat sink segments are fixedly secured together once connected. This can be achieved by welding, permanent adhesive bonding, etc. In another embodiment, a relative movement between the heat sink segments is possible once connected together. In this case, the heat sink segments become fixedly secured together once attached to the object to be cooled. It should be understood that more than one assembling means can be used for connecting the individual integral heat sink segments together. For example, a combination of male/female connector and adhesive bonding can be used.

In one embodiment, a heat sink having a shape similar to the heat sink 10 is made in multiple steps. The heat sink is divided into several heat sink segments, each one having dimensions adapted to be fabricated while using the extrusion process. The different heat sink segments are then assembled together to form a large heat sink having a shape such as the shape of heat sink 10.

It should be understood that heat sinks having any shape can be fabricated while using the process illustrated in FIG. 2. A complete heat sink having a given shape is broken down into at least two pieces or segments which are made in a single piece by extrusion. The breaking down of the complete heat sink is made so that each resulting individual heat sink segment can be fabricated integrally. The different segments are then assembled together to create the heat sink of the given shape.

FIG. 3 illustrates the top view of a heat sink segment 120 in accordance with an embodiment. The heat sink segment 120 corresponds to a quadrant of a cylindrical heat sink 150 illustrated in figure. The heat sink segment 120 is made of a single piece of heat conductive material. The heat sink segment 120 is provided with fins 124 on one of its lateral surfaces. A central aperture 126 extends from the top surface to the bottom surface (not shown) of heat sink segment 120. The fins 124 and the aperture 126 allow the surface of heat sink segment 120 that is in contact with the cooling fluid to be increased. The heat sink segment 120 is also provided with a circular recess 128 and a projecting end 130, which extend along a length of the heat sink segment 120. The shape and dimensions of the circular recess 128 and the projecting end 130 are adapted to form a male/female connector so that the projecting end 130 of one heat sink segment 120 can fit into a circular recess 128 of another heat sink segment 120. The heat sink segment 120 is also provided with a round surface 132 opposite to the lateral surface having fins 124 and a recess 134, 136 on the other two lateral surfaces. The recess 134 is adjacent to the circular recess 128 while the recess 136 is adjacent to the projecting end 130.

The heat sink 150 is created by assembling four identical heat sink segments 120 together, as illustrated in FIG. 4. The projecting end 130 of one heat sink segment 120 fits into the circular recess 128 of a next heat sink segment 120 like a tenon fits into a mortise. This secures the four heat sink segments 120 together to give rise to the heat sink 150. The resulting heat sink 150 has a cylindrical shape and presents the fins 124 that extend along its external lateral surface. The apertures 126 extend from the top surface to the bottom surface of the heat sink 150. An aperture 152 having the shape of a cross is formed by the round surface 132 and the recesses 134 and 136 of each heat sink segment 120. The aperture 152 also extends from the top surface to the bottom surface of the heat sink 150.

In one embodiment, each circular recess 128 is closed at one end, thereby forming an abutting surface. Each projecting end 130 is inserted in its corresponding circular recess 128 via the open end of the corresponding circular recess 128 and slides therein until abutting against the closed end of the corresponding recess 128. In another embodiment, the circular recesses 128 are each provided with an open end at their two extremities. In this case, the heat sink segments 120 can have a longitudinal relative movement. In order to fixedly secure the heat sink segments 120 together, any adequate type of mechanical fasteners such as screws, bolts, etc, can be used. Alternatively, any adequate type of adhesive can be used for securing the heat sink segments together. In another embodiment, the heat sink segments 120 become fixedly secured together once the heat sink 150 is attached to the object to be cooled.

While FIGS. 3 and 4 refer to recesses 128 and projecting ends 130 having a circular shape, it should be understood that they can be provided with any shape that allows a heat sink segment to fit and/or to slide into another heat sink segment in order to form a heat sink. For example, a recess and a projecting end each having a T-shape is also possible. Any adequate type of mechanical male-female connectors can be used for connecting the heat sink segments 120 together.

FIG. 5 illustrates one embodiment of a heat sink segment 160 which corresponds to a quadrant of a cubic heat sink 170 illustrated in FIG. 6A. The heat sink segment 160 is made of a single heat conductive piece having a substantially cubic shape. The heat sink segment 160 is provided with a round surface 164 and an aperture 162 extending through from one face to an opposite face of the heat sink segment 160.

FIG. 6A illustrates a heat sink 170 made of four identical heat sink segments 160, in accordance with one embodiment. The four heat sink segments 160 are secured to each other by adhesive bonding 172 in order to form heat sink 170. The adhesive used to secure the heat sink segments 160 together is chosen to be resistant to the temperature of the heat sink 170. The resulting heat sink 170 presents a central aperture 172 which is formed by the round surface 164 of the heat sink segments 160, and four apertures 162 extending from the front face to the rear face of the heat sink 170.

It should be understood that any mechanical means can be used to connect the single piece heat sink segments together to form the modular heat sink. The mechanical means can be either permanent or non-permanent. For example, the heat sink segments can be designed so that they fit together and assembly results in the modular heat sink. In another example, a permanent or non-permanent adhesive can be used to connect the heat sink segments together. The heat sink segments can also be welded together. FIG. 63 illustrates one embodiment of a heat sink 176 which uses straps 178 in order to maintain the assembly in position. The heat sink 176 is made of four heat sink segments 160 and has the same shape and dimensions as the heat sink 170, The straps 178 surround the heat sink segments 60 and maintain them in position. A combination of different assembling means, such as a combination of a male/female connector and an adhesive bonding, can also be used.

FIG. 7 illustrates another example of a heat sink segment 180 that can be used to make a heat sink similar to heat sink 170. The heat sink segment 180 is made in a single piece using usual extrusion technique. The heat sink segment 180 is provided with a central penetrating aperture 182 and four penetrating apertures 184. The heat sink segment 180 has a similar shape as heat sink 170 but its width is half the width of heat sink 170 and is therefore not adapted for an adequate cooling.

FIG. 8 illustrates a side view of a heat sink 186, in accordance with one embodiment. The heat sink 186 is made of two identical heat sink segments 180 which are stacked together. The two heat sink segments 180 are secured together by an adhesive bonding 188. The heat sink 186 has the same shape and dimensions as the heat sink 170. Alternatively, the heat sink segments 180 may be connected together using any adequate type of connection means or combination of connection means such as a male/female connector for example.

While the previous embodiments refer to a modular heat sink composed of N identical heat sink segments, it should be understood that the N heat sink segments can have different shapes as long as each one of the N heat sink segments corresponds to 1/N of the heat sink, and can be made of different materials, such as copper.

FIG. 9A illustrates the top view of a modular heat sink 200 comprising four individual integral heat sink segments 202, 204, 206, 208. The four heat sink segments 202, 204, 206, 208 are connected together by a releasable connection such as a non-permanent adhesive bonding for example. Each heat sink segment 202, 204, 206, 208 is provided with an aperture 210, 212, 214, 216 which extends from the top face to the bottom face of the heat sink segment 202, 204, 206, 208. The heat sink 200 can be used to cool a heat generating device which generates heat uniformly along its surface upon contact with the heat sink 200. If the heat generating device is replaced by another device which generates heat non-uniformly along its surface, such as a device that generates more heat in a region in contact with the heat sink segment 204, the heat sink 200 will no longer be adapted to cool the heat generating device. If a standard heat sink made in a single piece is used to adequately cool the device, a new heat sink adapted to the new heat generating device has to be provided. If the heat sink is the modular heat sink 200, only the heat sink segment 204 facing the hottest region of the new device can be changed.

FIG. 9B illustrates the top view of a heat sink 220 which is adapted to cool the new device which non-uniformly generates heat, according to one embodiment. The heat sink 220 is similar to the heat sink 200 but the heat sink segment 204 is replaced by the heat sink segment 222 which is fabricated using the extrusion process. The heat sink segment 222 is provided with four apertures 224 which extend from the top surface to the bottom surface of the heat sink segment 222. In comparison to the heat sink segment 204, the heat sink segment 222 provides greater cooling since it is provided with four apertures 224.

The heat sink 220 represents an example of a non-symmetrical heat sink. The heat sink segments 202, 206, 208, and 222 are not identical but each one of the heat sink segments 202, 206, 208, and 222 corresponds to 1/4 of the heat sink 220.

It should be understood that the heat sink segments 202-208 and 222 can be shaped so that the heat sinks 200 and 220 are provided with fins such as fins 224 on their outer lateral surface.

It should be understood that the modular heat sink can have any shape and/or dimension. The heat sink segments constituting the modular heat sink can also have any shape and/or dimensions as long as they form the modular heat sink when they are assembled together.

It should be understood that any material having good thermal conductivity such as aluminum or copper can be used to fabricate the heat sink segments.

It should be noted that modular heat sinks can be used to cool any devices which generate heat, such as lighting systems, electronic circuits, and the like.

The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims. 

1. A method for fabricating a modular heat sink, said method comprising: extruding N individual integral heat sink segments using an extrusion process, each one of said N segments corresponding to 1/N of said modular heat sink. N being an integer greater than one; and assembling said N individual integral heat sink segments together in order to obtain said modular heat sink.
 2. The method as claimed in claim 1, wherein said extruding comprises extruding N identical individual integral heat sink segments.
 3. The method as claimed in claim 1, wherein said extruding comprises extruding at least two different individual integral heat sink segments.
 4. The method as claimed in claim 3, wherein said extruding comprises extruding said at least two different individual integral heat sink segments having a different shape.
 5. The method as claimed in claim 3, wherein said extruding comprises extruding said at least two different individual integral heat sink segments from different materials.
 6. The method as claimed in claim 1, wherein said assembling comprises releasably connecting said N individual integral heat sink segments together.
 7. The method as claimed in claim 1, wherein said assembling comprises permanently securing said N individual integral heat sink segments together.
 8. The method as claimed in claim 1, wherein said extruding comprises extruding N connectable individual integral heat sink segments, each having a male connector and a female connector thereon, said female connector of each one of said N connectable individual integral heat sink segments being adapted to receive said male connector of another one of said N connectable individual integral heat sink segments
 9. The method as claimed in claim 8, wherein said extruding comprises extruding four quadrants of a cylindrically shaped modular heat sink.
 10. The method as claimed in claim 1, wherein said extruding comprises extruding said N individual integral heat sink segments from one of aluminum and copper.
 11. A modular heat sink comprising N extruded individual integral heat sink segments connected together to form said modular heat sink, each one of said N segments corresponding to 1/N of said modular heat sink. N being an integer greater than one.
 12. The modular heat sink as claimed in claim 11, wherein said N extruded individual integral heat sink segments are identical.
 13. The modular heat sink as claimed in claim 11, wherein at least two of said N extruded individual integral heat sink segments are different.
 14. The modular heat sink as claimed in claim 13, wherein said at least two of said N extruded individual integral heat sink segments have a different shape.
 15. The modular heat sink as claimed in claim 13, wherein at least one of said N extruded individual integral heat sink segments is made from a different material.
 16. The modular heat sink as claimed in claim 11, wherein said N extruded individual integral heat sink segments are releasably connected together.
 17. The modular heat sink as claimed in claim 11, wherein said N extruded individual integral heat sink segments are permanently secured together.
 18. The modular heat sink as claimed in claim 11, wherein each one of said N extruded individual integral heat sink segments comprises a male connector and a female connector thereon, said male connector of each of said N extruded individual integral heat sink segments being received in said female connector of another one of said N extruded individual integral heat sink segments.
 19. The modular heat sink as claimed in claim 11, wherein said N extruded individual integral heat sink segments are made of one of aluminum and copper.
 20. The modular heat sink as claimed in claim 11, wherein said N extruded individual integral heat sink segments are four quadrants of a cylindrically shaped modular heat sink. 